x=-3:.01:3;y=-2:.01:2;[XX,YY]=meshgrid(x,y);m=(625+0.75*YY.^2+0.75*XX.^2+156.25+20.91*XX).^0.5*120/(156.25+20.91.*XX+0.75*XX.^2);surf(XX,YY, m)
